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Things we figured out ...

Tobi Oetiker, 2013-02-09

DRBD is a distributed block level remote replication solution. Initially it was designed for machines sitting side by side with a dedicated network link between them. It does work well for remote setups as well, given proper tuning. OpenVPN, 'the standard' VPN system for Linux, can be used to provide compressed secure connections.

Tobi Oetiker, 2012-09-17

With Oracle seeming to focus entirely on large account solaris based setups for their SunRay system, it was time for us to find a new ThinClient desktop environment. Test.

Tobi Oetiker, 2011-11-23

If you are using SVN from windows, you will most likely have TortoiseSVN installed. Starting with version 1.5 provides an COM interface to read SVN keyword properties from within any language capable of accessing COM components.

Tobi Oetiker, 2010-05-12

I have recently switched to the latest Ubuntu release. As usual after such an operation, everything was all new and beautiful. And also as usual, some things did not work anymore. In the sections below you can find a list of things I have done to make my setup work for me.

Tobi Oetiker, 2009-10-18

We run a busy Linux file server providing both NFS and Samba file access, backed by a hardware RAID6 running a ext3 filesystem. Experience tells me that the worst performance is to be expected when there are competing read and write accesses to the file system. Looking at existing benchmarks, this pattern does not seem to get exercised a lot.

Tobi Oetiker, 2008-06-08

Hardware RAID boxes are cool things. Plug them in and they behave like a big and fast disk. If properly configured, they'll be another 30% faster.

Tobi Oetiker, 2007-05-21

The file system cache (buffer cache) helps programs to get to their data blocks faster by keeping recently used file blocks in memory. If you copy a large file tree, this has a devestating effect on the cache since all the copied data will also end up in the cache, force other data blocks out of the cache. This is very bad for system performance since of all the other processes on the system that had their data blocks in the cache before the copying started will suddenly have to read data from disk again. Using posix_fadvise you can hint the OS that it should drop certain file blocks from the cache. Together with information from mincore that tells us which blocks are currently cached we can alter applications to work without disturbing the buffer cache. This article shows how this works, using rsync as an example.

Tobi Oetiker, 2007-05-04

Rule number one: Don't Panic!. Think twice before you do anything. Rule number two: If you did panic, there is still hope.


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